Ink composition



Patented Dec. 6,1938

INK COMPOSITION Samuel A. Neidich, Burlington, N. J., assignor, by mesne assignments, to Underwood Elliott Fisher Company, New York, N. Y., a corporation of Delaware No Drawing.

2 Claims.

The ink composition to which this invention is directed, is primarily designed for application to or the impregnation of ink carriers, such as flexible ribbons of absorbent fabric or of other suitable material, or carbon sheets, for use in typewriting machines, registers, printing machines andpresses, in wide or narrow lengths.

Recent experiments have been conducted for the purpose of developing a flexible ribbon, not particularly absorptiveby nature, such as Cellophane, paper or the like, which carries the ink or impression composition as a coating, and the ink composition hereinafter set forth is applicable to such ribbons, as well as to those composed of absorbent fabric.

Heretofore, in the manufacture of ink for impregnation or coating of ribbons for use in typewriting or other printing machines, it has been customary to grind the selected pigment, as carbon black, for example, with one or more nondrying oils, which experience has taught give the best results. I

some aniline base may be mixed with the above ingredients asa toning agent, if desired, after which the ribbons are coated, impregnated or saturated with the ink thus compounded.

Deterioration, however, occurs in ribbons kept in stock, the ink dries out, and the effective life of the ribbon is materially-shortened, which deterioration is not wholly accounted for by the gradual absorption of the ink into the innermost Application November 23, 1935, Serial No. 51,202

cores of the fibres composing the ink carriermaterial or fabric, or by evaporation.

Also it is well known that the characteristics of even the more highly refined, non-drying oils v of animal or vegetable origin change, upon long exposure to the air, and the oils tend to oxidize, and even become rancid. 1

Due possibly to such changes, the oils used compounding ribbon inks always become more 40 fluid in warm weather than in cold weather, so

that the ribbons part with' their ink content more freely, thus reducing the length of time during which distinct impressions can be made on. the record material.

Attempts have been made to overcome this exdepositing on problems from a diiferent angle, and'instad of attempting to control the ink content in its more fluid state, I have sought to prevent the ink from becoming fluid and also to prevent deterioration of the ink through oxidation. Furthermore, the 5 5 invention, results in the production of a more 4 stable ink, the non-drying properties of which are prolonged, to impart extended life to the ribbon. To these ends, I have discovered that the foregoing disadvantages are obviated to all practical purposes, by the use of certain compounds of that group containing tri-cresyl phosphate,

which not only eliminates the former objections,

but in addition, makes available a ribbon in which the colors are more thoroughly dispersed in the ink; which does not change in character even after long exposure to the air, and which maintains the ink composition at a substantially with this new ink compound is gradually exhausted at an even rate while the ribbon is in use, which also tends to prolong the effective life of the ribbon and the impressions are of even intensity, assuming that the impact or pressure of the types is evenly applied, thus achieving the important advantage of eliminating the cause of variations in type impressions at the source, instead of attempting to physically restrain an excess deposit of ink in typing on the work sheet after the ink heretofore compounded, has become unduly fluid.

As an illustration ,of the use of my improved ink composition, wherein tricresyl phosphate is 3 substituted for the entire oil content heretofore I used in ribbon inks as a vehicle for the pigments, the following formula may be taken as an example, which is applicable to ink carriers 'used in connection with a wide variety of ma- .chines, as typewriting and adding machines. Multigraph and other duplicators, printing presses, and the like, the proportions being given by weight.

One such working formula contains Parts 55 Tri-cresyl phmph ate Oleic acid v Qarbon black or other suitable pigment depending upon the color of ink desired Nigrosine or other aniline base as a toning agent 8 The foregoing proportionsarepintended for illustration only, some variation-being, of course, 55

the advantages mentioned.-

It will be noted that the above listed ingredients are all well-known in the manufacture of inks for the purpose stated, with'the exception of the tri-cresyl phosphate, which is used as a vehicle for the selected pigments, and which, so far as I am aware, has never been used in the composition of ribbon inks. h

The ink, under the above formula, is compounded and applied in the same manner as heretofore; the carbon blackor othercolor pigments'meipg mixedtogether and ground with thenon-drying tricresyl phosphate in a suitable mill,

and toned, by mixing therewith a suitable color base, which is soluble in the presence of an oil miscible acid, such as oleic acid.

m improvement contemplates the substitution -of tri-cresyl phosphate for part or all of the oil.

As an example of a formula wherein the tricresyl phosphate is substituted for a part only of the oils of animal or vegetable origin, I suggest Parts by weight Tri-cresyl phosphate 50 Castor oil 50 Carbon black 20 Prussian blue toning base 20 the particular proportions given, being subject to some variation.

Tri-cresyl phosphate, by reason of its exceptionally low surface tension and vapor pressure, apparently imparts the best results when commingled with the other ingredients of the ink composition, but other organic esters, as triphenyl phosphate, dibutyl phthalat e, diamyl phthalate and diethyl phthalate, having the physical properties of an oil, and the characteristics of low surface tension and low vapor pressure will serve nearly as well, when, like tricresyl .phosphate, they are used in quantities sufficient to act as vehicles for the selected pigments.

"Nigrosine mentioned in the first formula, is the trade name for a base color or aniline dye. The inclusion of trL-cresyl phosphate or an equivalent compound, to the ink or dope with which manifolding paper, known as carbon paper, is coated, tends to toughen the dope or ink composition, thereby resulting in materially increasing the durability of the sheet or paper in actual service or work.

A' sample formula for carbon paper ink or dope" utilizing my discovery, is

Parts by weight Petrolatum oil '76 Tri-cresyl phosphate, or any equivalent compound having the above enumerated properties and characteristics 24 Carnauba wax 92 Carbon black 36- Methyl violet or other toning color '7 possible in obtaining an ink composition having tri-cresyl phosphate, carbon black and the toning agent to the exact amounts specified, reasonable variations thereof being permissible.

Petrolatum oil is a mineral oil of light gravity and low viscosity, preferably of the class of very light oils used medicinally. However, other nonjellies ground withblack or other pigments, and

toned with color bases or basic colors, the latter being soluble in oils in the presence of organic acids, as oleic acid, for example, and the pigments distinguishable therefrom, by being soluble in water.

In my invention, the ingredient tri-cresyl phosphate or its equivalent, being of an oily nature, is substituted for a part or all of the oil or petroleum jelly usually included to soften or reduce the hardness of the wax.

Conveniently, the ingredients are melted together and then ground on a cold three roller mill, a heated centrifugal or ball mill, or any of the various types of colloid mills. Or accord- .ing to commercial practice. the various ingredients are weighed out in their respective proportions, and thrown into a suitable grinding mill, as a three rollermill, which thoroughly amalgamates the different materials and disperses the pigment, as carbon black, thoroughly throughout the'mass.

Where the ingredients are ground in a heated mill, the heat is held substantially to that degree accordant with a pressure of ten pounds of steam in the heating jacket of the mill. In any case, only sufficient heat is applied to retain the carbon ink in a molten state.

In grinding carbon dope in a three roller mill, the rolls are kept cold and the ink issues from the mill in plastic scales.

The term base as used in connection with the words aniline, Nigrosine, color, and toning is commonly used in the dye-stuff trade, and has but one meaning, as follows.

There is a class of dye-stuffs, the more important of which are Crystal and Methyl Violet Purple Victoria Blue Blue Victoria Green Green Rhodamine Red Auramine Yellow Nigrosine Black Each of these colors or dye-stuffs is an ester of a complicated organic chemical radical having the corresponding coloring properties.

. These dye-stuffs or colors are generally sold as chlorides or zinc chlorides. For example, Methyl Violet is a zinc chloride of penta methylpara rosaniline.

These dye-stuffs have, in common, the property of being completely and easily soluble in water, andin such solution are used in ordinary dyeing operations, for dyeing paper, and paper pulp, for instance.

If these colors or dye-stuffs in water solution. are treated with an alkali, as soda ash, for example, the color precipitates out of the water solution, as a base, an OK radical replacing the Cl radical, to form water-insoluble, aniline bases, which are known in the trade as Methyl Violet Base, Nigrosine Base, etc.

When these base colors are treated with an acid miscible with oils, as oleic acid, for instance, or other suitable solvent, there is formed a strong, oily solution (oleic acid being regarded chemically as a fatty acid) of the respective colors, and when used in compounding ribbon inks, the solution strongly dyes the oils or miscible ingredients of such ink compound.

This solution of a base color with'an acid miscible with oils is a toning agent, and has the following purpose.

A ribbon saturated with an ink composed only of an oil or other medium into which is ground carbon black, would give an imprint or write dirty brown in color. Therefore, a "toning agent, or aniline base", as a Nigrosine base,

' when describing a black toning agent, is added to the carbon black suspended in the tricresyl phosphate vehicle, to develop the extremely strong, rich black imprint demanded of modern typewriter ribbons.

Tri-cresyl phosphate, as one element of a number of hydrocarbon derivatives suitable for use as a control and preservative ingredient in ribbon and carbon paper inks, is well known, and- I am aware of its use in connection with other constituents, as a bonding medium employed as an adhesive, wherein it constitutes by comparison, an ahnost negligible part of the blended composition.

I also am aware of the use'of this compound in the manufacture of imitation embossed printing, and in the manufacture of decalcomanialike transfers, but in none of these prior uses, is the tri-cresyl phosphate or its equivalent used for the purposes set forth in my invention, nor

in combination with the kinds of ingredients hereinbeiore referred to.

Changes may be made in the proportions set forth, and in the particular preservative hydrocarbon derivative other than those mentioned, without departing from the spirit and'scope of my invention, the essence of which resides in the use of a hydrocarbon derivative of the group to which tri-cresyl phosphate, dibutyl-, diamyland diethyl-phthalates belong, having an oily nature, with low vapor pressure and low surface tension, as an ingredient of an ink composition for saturating, impregnating or coating ribbons and carbon sheets for use in printing presses, typewriting, adding, and autographic machines and recorders, to maintain the ink substantially uniform in density despite variations in temperature and humidity, and prevent deterioration of. the ink due to exposure or age.

What I claim as new, is:

1. A ribbon ink composed of a pigment; tri-' cresyl phosphate in quantity sufiicient to serve as the vehicle in which the pigment is dispersed and held in suspension; a basic color base to intensify and enrich the color of the pigment; and oleic acid to dissolve the basic color base.

2. A ribbon ink composed of the following ingredients by weight; 12 parts of pigment; 55 parts of tricresyl phosphate as the vehicle in which the pigment is held in suspension; and 8 parts of a basic color base dissolved in parts of oleic acid to dye the tricresyl phosphate vehicle and intensify, tone and enrich the color of the mixture. I

. SAMUEL A. NEIDICH. 

